I have this homebuilt AC30ish amp.Its 2 channels, 1 is EF86 and the other is 12ax7, Channel 1 is fine but channel 2 has a high pitched hissing sound only when channel 1 volume is at 0, turning it up makes it stop. It also sounds like vol 1 is acting like a tone control for channel 2 if that makes any sense. Vol 1 at 0 makes channel 2 very trebley, turning it up makes the hiss stop and changes the tone of channel 2 and kinda flattens it out. Any ideas on where to look before I tear it all down and rebuild?
What if you tear it down, rebuild, and it does the same thing? Troubleshooting is about finding what is wrong and fixing that. Do you have a scope? You might have a channel oscillating at RF. That often manifests itself as a hum or hiss and thin audio. And correcting that might be more about lead dress and grounding than build errors or bad parts.
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